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Anaplasma marginale major surface protein 3 is encoded by a polymorphic, multigene family
A R Alleman1, G H Palmer, T C McGuire
1Department of Physiological Sciences, University of Florida, Gainesville 32610, USA. ARALL@GNV.IFAS.UFL.EDU
Infection and Immunity
|January 1, 1997
Summary
Anaplasma marginale uses a polymorphic multigene family to vary its surface protein MSP3, contributing to antigenic variation. This genetic diversity may explain persistent infections in cattle.
Area of Science:
- Veterinary Microbiology
- Molecular Biology
- Immunology
Background:
- Anaplasma marginale, a significant cattle pathogen, exhibits antigenic variation in its surface proteins.
- The immunodominant surface protein, MSP3, shows considerable structural and antigenic polymorphism across different strains.
Purpose of the Study:
- To investigate the genetic basis of MSP3 polymorphism in Anaplasma marginale.
- To determine if multigene families contribute to the antigenic variation of MSP3.
Main Methods:
- Cloning and expression of the A. marginale msp3-12 gene in Escherichia coli.
- Using msp3-12 as a probe to identify homologous gene copies in A. marginale genomes.
- Sequence analysis of identified msp3 gene variants.
Main Results:
- Multiple, partially homologous msp3 gene copies were detected in the genomes of three A. marginale strains.
- These msp3 gene copies were distributed throughout the bacterial chromosome.
- Sequence analysis revealed conserved and variant regions within msp3 genes, with some amino acid blocks related to MSP2.
Conclusions:
- A polymorphic multigene family is at least partially responsible for the variation in Anaplasma marginale's MSP3 protein.
- Multigene families are likely employed by A. marginale to vary key antigenic surface proteins.
- These findings offer insights into the antigenic variation mechanisms driving persistent infections in carrier cattle.